The role of water reservoirs in formation of physicochemical characteristics of river waters on the Ciosenka river example

The A2 motorway exploitation as well as the settlement and agriculture play a principal role in the formation of the physicochemical characteristics on the Ciosenka catchment. The retarding and infiltration basins system is controlled at the P1 and P2 outlets, and at settling tank - P3. It directs waters from the A2 motorway towards the Ciosenka valley at P4. In the valley there are Rosanow large spring (P5) and three flow-through water reservoirs (P6-P7). The measurements of the specific conductance, alkali level, dissolved oxygen, water temperature and turbidity were performed on the seven stations located along the river bed. In this paper, the transformation rate of the physicochemical aquatic environment characteristics and its seasonal distribution were presented. Based on longterm characteristics the monthly averages and yearly medians also Markham 's seasonality indexes are counted. Below water discharge place form the motorway drainage, a slight increase of the electrolytic conductance and reactions changes were cyclically registered. Furthermore, the analysis of the data series has proved that physicochemical characteristics are modified by the seasonal rhythm. It has been found that the long-term median water temperature being aligned (about 10°C) and its amplitude increases with the passage up the river. The temperature maximum fell in all cases in July, the minimum temperatures fell in February. The electrical conductivity showed that the maximum SEC values are observed in winter (till 21,3 mS·cm⁻¹ in outlets), as same as in waters of Ciosenka river (340-440 μS ·cm⁻¹) , but the dates of concentration of conductivity are registered in June. Furthermore, every time in spring, the conductivity of water in settling tank has been changed by a mixing of surface waters with bottom ones (thermal turnover). The average water pHs hasn 't big spatial and time diversity, but in the measurement point, situated beneath the A2 motorway, the water pH in the winter months is slightly more alkaline (up to 8.4 in March) than in the summer months (7.5 in June). Below the flow-through reservoirs the acidity of water is a bit lower, but the amplitude is significant. The highest oxygen concentration in river waters was registered during winter and spring season with relatively low water temperature. The intensity of this processes is related to the water reservoir temperature increase, to the limitation of the surface runoff and water plants growth phases. The turbidity of river water isn 't strictly dependent on supply of road sewages. Higher turbidity is characteristic for the months with poor flora development (III-V) or for the heavy precipitation periods (VII-IX). The reservoirs reduce mainly the amount of allochtonic matter being at the same time the sources of new suspensions